Technology eReport
Volume 5, Number 4
November 2006

Table of Contents
Past Issues

Virtual Private Networks over the Public Internet

By Sean La Roque-Doherty

 Imagine that you have a private, secure road between your home and office, dedicated to your use. Now imagine that the road is over the Internet and your vehicle is a PC or laptop. In effect, the road is a virtual private network (VPN) that can save you time and money.

A VPN allows you to send data between two computers across a shared, public network like the Internet in a way that emulates the properties of a point-to-point private link. In effect, it’s the next best thing to being physically on the remote network and plugging your computer into it or being close enough to allow wireless access.

VPNs sound a bit like remote control, right? A bit, but remote control is a software application that allows a remote computer to connect to a host computer to control the host’s resources. A VPN, on the other hand, virtually puts a remote computer onto the same network as your law office where there may be a time and billing server and file, print, and fax servers to share.

A VPN saves you the time and expense of either traveling to the office or replicating office resources onto a PC or laptop. But if all you have in your law office is a computer with directly connected peripherals, such as a printer, then setting up a VPN is not worth your time. Look at a remote control program.

A remote control program like Symantec’s pcAnywhere or MS-Windows Remote Desktop tool or a service like GoToMyPC ( will get you from remote computers to your office computer and its resources. And if you need to traverse a firewall at the office, allow remote control packets to pass through the firewall directly to your office computer on the TCP (transmission control protocol) port used by the remote control program.

VPN for the Solo and Small Office Practitioner
There are different types of VPNs: Intranet, extranet, and remote access. Intranet and extranet VPNs interconnect central offices with branch offices and corporate sites with partners or customers, respectively. Remote access VPNs are VPNs for telecommuters and mobile or remote workers like the solo and small office practitioner when they are out of the office.

A basic premise for the remote access VPN is that the remote worker, you, must have access to the Internet via a dial-up or broadband (cable or DSL/ADSL modem) connection. Then, a secure communications channel can be established from the remote location to the office using VPN software installed on end points such as a PC, laptop, or home router and the office router.

The level of bandwidth available to the VPN will depend on the speed of the remote connection between your home and the Internet and your law office and the Internet. Other factors include the total volume of traffic over those links and the level of congestion experienced on the Internet. After all, the Internet is a shared medium with variable issues in access and congestion control as well as security concerns.

VPN Technology
In a VPN, the connection between a remote computer or remote SOHO and the law office has two parts. In one part, the private data is encapsulated. That’s called the tunnel. In the other part, data is encrypted. That’s known as the VPN connection (see Figure 1).

 VPN connections and tunnels allow users working at home or other remote locations to connect to a remote device in a secure fashion using the routing infrastructure provided by the Internet. Hence, the same dial-up or broadband connection you use at home for work and entertainment will get you to the office. So there’s no dedicated long-distance or toll-free phone number to call and no dedicated, physical connection to set up.

A VPN emulates a point-to-point link by encapsulating data. Data encapsulation puts data in a wrapper and labels the wrapper with routing information. When your computer transmits the wrapper, the routing information enables it to traverse the Internet to reach its endpoint, the remote office network. To add privacy, the data being sent is encrypted for confidentiality. That way, any packets that are intercepted on the public Internet are not readily decipherable without the encryption keys.

From the end user’s perspective, the VPN connection is a point-to-point connection between the home or remote computer and a law office network. The nature of the Internet between the two is irrelevant, because data is being sent over a virtual, dedicated private link. In effect, your remote computer will find all your office resources as if it was in the office.

How Do You Get a VPN?
Obtaining VPN software can be like obtaining other technology today. You may already own it and don’t know it. That is, it may already be resident in your home or office router ready for use.

For example, some Linksys and Netgear routers have VPN client/server software resident on their devices. All you need to do is obtain the client software for your PC or laptop. Linksys uses Quick VPN ( and Netgear uses Prosafe VPN client software ( In addition, it is possible to set up a VPN between your home and office routers.

Setting up a VPN between home and office routers is easy if the routers are manufactured by the same vendor such as Cisco Systems, Inc. (Linksys) or Netgear and you happen to have a teenager resident on your network. Otherwise, the configuration issues may warrant help from a service provider. For example, you will want to make sure your home network is completely secure before connecting it to the office.

You can also purchase a turn-key (hardware and software) VPN solution from the likes of Juniper Networks ( But that is a bit extravagant for the solo and small office practitioner. As an alternative, look into the VPN software built into Microsoft Windows and your office router.

See if your office router supports PPTP (Point-To-Point Protocol) or L2TP (Layer 2 Tunneling Protocol) tunneling protocols. PPTP was initially developed by Ascend and Microsoft Corp. and is embedded in Windows. It is a proprietary technique that encapsulates Point-to-Point Protocol (PPP) frames in IP packets. Packet filters provide access control from end-to-end.

L2TP is an open, standards-based tunneling protocol. It grew out of a combination of the Point-to-Point Tunneling Protocol (PPTP) and Cisco System’s proprietary Layer 2 Forwarding (L2F) protocol.

If your office router supports either PPTP or L2TP, you can enable that software and set up users from the router’s administrative interface. Then you can use Microsoft’s New Connection wizard on the remote PC or laptop to set up a new network connection with your office. Again, resident teenagers work wonders in the setup process.

If you have set up a law office network with time/billing software and file, print, and fax servers, setting up VPN access to that network will save you the time and money of replicating those resources on other computers when you work from home or on the road. VPNs are easy to set up, and you may already own the software to get started.


Sean La Roque-Doherty is a solo practitioner licensed to practice in California, the District of Columbia, and New York. His practice focuses on computer and telecommunications law, copyright, trademark, and privacy. He can be reached at




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